Adjuvant pioglitazone for unremitted depression: Clinical correlates of treatment response

Metabolic complications of psychotropic medications in psychiatric disorders: Emerging role of de novo lipogenesis and therapeutic consideration

Although significant advances have been made in understanding the patho-physiology of psychiatric disorders (PDs), therapeutic advances have not been very convincing. While psychotropic medications can reduce classical symptoms in patients with PDs, their long-term use has been reported to induce or exaggerate various pre-existing metabolic abnormalities including diabetes, obesity and non-alcoholic fatty liver disease (NAFLD). The mechanism(s) underlying these metabolic abnormalities is not clear; however, lipid/fatty acid accumulation due to enhanced de novo lipogenesis (DNL) has been shown to reduce membrane fluidity, increase oxidative stress and inflammation leading to the development of the aforementioned metabolic abnormalities. Intriguingly, emerging evidence suggest that DNL dysregulation and fatty acid accumulation could be the major mechanisms associated with the development of obesity, diabetes and NAFLD after long-term treatment with psychotropic medications in patients with PDs. In support of this, several adjunctive drugs comprising of anti-oxidants and anti-inflammatory agents, that are used in treating PDs in combination with psychotropic medications, have been shown to reduce insulin resistance and development of NAFLD. In conclusion, the above evidence suggests that DNL could be a potential pathological factor associated with various metabolic abnormalities, and a new avenue for translational research and therapeutic drug designing in PDs.

Emerging Perspectives on the Impact of Diabetes Mellitus and Anti-Diabetic Drugs on Premenstrual Syndrome. A Narrative Review

Diabetes mellitus (DM) and premenstrual syndrome (PMS) are global health challenges. Both disorders are often linked to a range of physical and psychological symptoms that significantly impact the quality of life of many women. Yet, the exact relation between DM and PMS is not clear, and the management of both conditions poses a considerable challenge. In this review, we aimed to investigate the interplay between DM, anti-diabetic drugs, and the different theories and symptoms of PMS. Female sex hormones are implicated in the pathophysiology of PMS and can also impair blood glucose control. In addition, patients with diabetes face a higher susceptibility to anxiety and depression disorders, with a significant number of patients experiencing symptoms such as fatigue and difficulty concentrating, which are reported in patients with PMS as well. Complications related to diabetic medications, such as hypoglycemia (with sulfonylurea) and fluid retention (with thiazolidinediones) may also mediate PMS-like symptoms. DM can, in addition, disturb the normal gut microbiota (GM), with a consequent loss of beneficial GM metabolites that guard against PMS, particularly the short-chain fatty acids and serotonin. Among the several available anti-diabetic drugs, those (1) with an anti-inflammatory potential, (2) that can preserve the beneficial GM, and (3) possessing a lower risk for hypoglycemia, might have a favorable outcome in PMS women. Yet, well-designed clinical trials are needed to investigate the anti-diabetic drug(s) of choice for patients with diabetes and PMS.

Efficacy and Safety of Antidiabetic Agents for Major Depressive Disorder and Bipolar Depression: A Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Trials

BACKGROUND

This meta-analysis aimed to determine the efficacy and safety of antidiabetic agents in the treatment of major depressive disorder and bipolar depression.

METHODS

Randomized controlled trials (RCTs) of antidiabetic agents in major depressive disorder or bipolar depression were searched in three electronic databases and three clinical trial registry websites from their inception up to October 2023. The differences in changes in the depression rating scale scores from baseline to endpoint or pre-defined sessions, response rate, remission rate, rate of side effects and dropout rate between antidiabetic agents and placebo were meta-analyzed.

RESULTS

Six RCTs involving 399 participants were included in the final meta-analysis, which did not find that antidiabetics outperformed the placebo in reducing depressive symptoms. The standardized mean difference (SMD) in the depression scores from baseline to endpoint was 0.25 (95% CI -0.1, 0.61). However, a subgroup analysis found a significant difference between antidiabetics and placebos in reducing depressive symptoms in Middle Eastern populations, with an SMD of 0.89 (95% CI 0.44, 1.34).

CONCLUSIONS

The current meta-analysis does not support the efficacy of antidiabetics being superior to the placebo in the treatment of unipolar and bipolar depression. However, a subgroup analysis indicates that patients from the Middle East may benefit from adding an antidiabetic medication to their ongoing medication(s) for their depression. Larger studies with good-quality study designs are warranted.

The role of polyunsaturated fatty acids in the neurobiology of major depressive disorder and suicide risk

Long-chain polyunsaturated fatty acids (LC-PUFAs) are obtained from diet or derived from essential shorter-chain fatty acids, and are crucial for brain development and functioning. Fundamentally, LC-PUFAs' neurobiological effects derive from their physicochemical characteristics, including length and double bond configuration, which differentiate LC-PUFA species and give rise to functional differences between n(omega)-3 and n-6 LC-PUFAs. LC-PUFA imbalances are implicated in psychiatric disorders, including major depression and suicide risk. Dietary intake and genetic variants in enzymes involved in biosynthesis of LC-PUFAs from shorter chain fatty acids influence LC-PUFA status. Domains impacted by LC-PUFAs include 1) cell signaling, 2) inflammation, and 3) bioenergetics. 1) As major constituents of lipid bilayers, LC-PUFAs are determinants of cell membrane properties of viscosity and order, affecting lipid rafts, which play a role in regulation of membrane-bound proteins involved in cell-cell signaling, including monoaminergic receptors and transporters. 2) The n-3:n-6 LC-PUFA balance profoundly influences inflammation. Generally, metabolic products of n-6 LC-PUFAs (eicosanoids) are pro-inflammatory, while those of n-3 LC-PUFAs (docosanoids) participate in the resolution of inflammation. Additionally, n-3 LC-PUFAs suppress microglial activation and the ensuing proinflammatory cascade. 3) N-3 LC-PUFAs in the inner mitochondrial membrane affect oxidative stress, suppressing production of and scavenging reactive oxygen species (ROS), with neuroprotective benefits. Until now, this wealth of knowledge about LC-PUFA biomechanisms has not been adequately tapped to develop translational studies of LC-PUFA clinical effects in humans. Future studies integrating neurobiological mechanisms with clinical outcomes may suggest ways to identify depressed individuals most likely to respond to n-3 LC-PUFA supplementation, and mechanistic research may generate new treatment strategies.

Cool the Inflamed Brain: A Novel Anti-inflammatory Strategy for the Treatment of Major Depressive Disorder

BACKGROUND

Abundant evidence suggests that inflammatory cytokines contribute to the symptoms of major depressive disorder (MDD) by altering neurotransmission, neuroplasticity, and neuroendocrine processes. Given the unsatisfactory response and remission of monoaminergic antidepressants, anti-inflammatory therapy is proposed as a feasible way to augment the antidepressant effect. Recently, there have been emerging studies investigating the efficiency and efficacy of anti-inflammatory agents in the treatment of MDD and depressive symptoms comorbid with somatic diseases.

METHODS

In this narrative review, prospective clinical trials focusing on anti-inflammatory treatment for depression have been comprehensively searched and screened. Based on the included studies, we summarize the rationale for the anti-inflammatory therapy of depression and discuss the utilities and confusions regarding the anti-inflammatory strategy for MDD.

RESULTS

This review included over 45 eligible trials. For ease of discussion, we have grouped them into six categories based on their mechanism of action, and added some other anti-inflammatory modalities, including Chinese herbal medicine and non-drug therapy. Pooled results suggest that anti-inflammatory therapy is effective in improving depressive symptoms, whether used as monotherapy or add-on therapy. However, there remain confusions in the application of anti-inflammatory therapy for MDD.

CONCLUSION

Based on current clinical evidence, anti-inflammatory therapy is a promisingly effective treatment for depression. This study proposes a novel strategy for clinical diagnosis, disease classification, personalized treatment, and prognostic prediction of depression. Inflammatory biomarkers are recommended to be assessed at the first admission of MDD patients, and anti-inflammatory therapy are recommended to be included in the clinical practice guidelines for diagnosis and treatment. Those patients with high levels of baseline inflammation (e.g., CRP > 3 mg/L) may benefit from adjunctive anti-inflammatory therapy.

Toward a Precision Treatment Approach for Metabolic Depression: Integrating Epidemiology, Neuroscience, and Psychiatry

Background

Individuals with comorbid major depressive disorder and type 2 diabetes represent an important subgroup of patients for whom conventional treatment may be insufficient. A precision treatment approach that addresses insulin resistance with an outcome of a positive response to antidepressants may prove beneficial.

Methods

This study utilized an emulated target trial on a large dataset from the Optum Clinformatics Data Mart Database. We evaluated the effect of adjuvant pioglitazone, an insulin-sensitizing drug, on antidepressant response among 4696 people with type 2 diabetes, comparing it with DPP4 (dipeptidyl peptidase-4) inhibitors (non-insulin-sensitizing). An additional analysis involving 6518 participants was conducted to assess the efficacy of pioglitazone versus sulfonylureas.

Results

The instrumental variable analysis indicated that the initiation of an antidepressant with pioglitazone was superior to DPP4 inhibitors in terms of antidepressant response, with fewer treatment shifts and/or additions of new antidepressant or antipsychotic over a 1-year period. This result was consistent when pioglitazone was compared with sulfonylureas in a supplemental analysis.

Conclusions

Our findings suggest that pioglitazone may be more effective than DPP4 inhibitors or sulfonylureas in enhancing antidepressant response among people with comorbid major depressive disorder and type 2 diabetes. This provides a strong case for the use of pioglitazone in patients with these conditions, emphasizing the potential of precision medicine strategies. The results should be interpreted with caution due to inherent limitations associated with observational data.

Brain insulin signaling as a potential mediator of early life adversity effects on physical and mental health

In numerous brain structures, insulin signaling modulates the homeostatic processes, sensitivity to reward pathways, executive function, memory, and cognition. Through human studies and animal models, mounting evidence implicates central insulin signaling in the metabolic, physiological, and psychological consequences of early life adversity. In this review, we describe the consequences of early life adversity in the brain where insulin signaling is a key factor and how insulin may moderate the effects of adversity on psychiatric and cardio-metabolic health outcomes. Further understanding of how early life adversity and insulin signaling impact specific brain regions and mental and physical health outcomes will assist in prevention, diagnosis, and potential intervention following early life adversity.

Sodium-Glucose Cotransporter-2 Inhibitors in Depression

ABSTRACT

Novel treatment strategies that refract existing treatment algorithms for depressive disorders are being sought. Abnormal brain bioenergetic metabolism may represent an alternative, therapeutically targetable neurobiological basis for depression. A growing body of research points to endogenous ketones as candidate neuroprotective metabolites with the potential to enhance brain bioenergetics and improve mood. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, originally approved for the treatment of diabetes, induce ketogenesis and are associated with mood improvement in population-based studies. In this column, we highlight the rationale for the hypothesis that ketogenesis induced by SGLT2 inhibitors may be an effective treatment for depressive disorders.

Impact of insulin and insulin resistance on brain dopamine signalling and reward processing- an underexplored mechanism in the pathophysiology of depression?

Type 2 diabetes and major depressive disorder (MDD) are the leading causes of disability worldwide and have a high comorbidity rate with fatal outcomes. Despite the long-established association between these conditions, the underlying molecular mechanisms remain unknown. Since the discovery of insulin receptors in the brain and the brain's reward system, evidence has accumulated indicating that insulin modulates dopaminergic (DA) signalling and reward behaviour. Here, we review the evidence from rodent and human studies, that insulin resistance directly alters central DA pathways, which may result in motivational deficits and depressive symptoms. Specifically, we first elaborate on the differential effects of insulin on DA signalling in the ventral tegmental area (VTA) - the primary DA source region in the midbrain - and the striatum as well as its effects on behaviour. We then focus on the alterations induced by insulin deficiency and resistance. Finally, we review the impact of insulin resistance in DA pathways in promoting depressive symptoms and anhedonia on a molecular and epidemiological level and discuss its relevance for stratified treatment strategies.

Understanding the Role of Oxidative Stress, Neuroinflammation and Abnormal Myelination in Excessive Aggression Associated with Depression: Recent Input from Mechanistic Studies

Aggression and deficient cognitive control problems are widespread in psychiatric disorders, including major depressive disorder (MDD). These abnormalities are known to contribute significantly to the accompanying functional impairment and the global burden of disease. Progress in the development of targeted treatments of excessive aggression and accompanying symptoms has been limited, and there exists a major unmet need to develop more efficacious treatments for depressed patients. Due to the complex nature and the clinical heterogeneity of MDD and the lack of precise knowledge regarding its pathophysiology, effective management is challenging. Nonetheless, the aetiology and pathophysiology of MDD has been the subject of extensive research and there is a vast body of the latest literature that points to new mechanisms for this disorder. Here, we overview the key mechanisms, which include neuroinflammation, oxidative stress, insulin receptor signalling and abnormal myelination. We discuss the hypotheses that have been proposed to unify these processes, as many of these pathways are integrated for the neurobiology of MDD. We also describe the current translational approaches in modelling depression, including the recent advances in stress models of MDD, and emerging novel therapies, including novel approaches to management of excessive aggression, such as anti-diabetic drugs, antioxidant treatment and herbal compositions.

Are the antidepressant effects of insulin-sensitizing medications related to improvements in metabolic markers?

Insulin-sensitizing medications were originally used in psychiatric practice to treat weight gain and other metabolic side effects that accompany the use of mood stabilizers, antipsychotics, and some antidepressants. However, in recent studies these medications have been shown to cause improvement in depressive symptoms, creating a potential new indication outside of metabolic regulation. However, it is still unclear whether the antidepressant properties of these medications are associated with improvements in metabolic markers. We performed a systematic search of the literature following PRISMA guidelines of studies investigating antidepressant effects of insulin-sensitizing medications. We specifically focused on whether any improvements in depressive symptoms were connected to the improvement of metabolic dysfunction. Majority of the studies included in this review reported significant improvement in depressive symptoms following treatment with insulin-sensitizing medications. Nine out of the fifteen included studies assessed for a correlation between improvement in symptoms and changes in metabolic markers and only two of the nine studies found such association, with effect sizes ranging from R² = 0.26-0.38. The metabolic variables, which correlated with improvements in depressive symptoms included oral glucose tolerance test, fasting plasma glucose and glycosylated hemoglobin following treatment with pioglitazone or metformin. The use of insulin-sensitizing medications has a clear positive impact on depressive symptoms. However, it seems that the symptom improvement may be unrelated to improvement in metabolic markers or weight. It is unclear which additional mechanisms play a role in the observed clinical improvement. Some alternative options include inflammatory, neuroinflammatory changes, improvements in cognitive functioning or brain structure. Future studies of insulin-sensitizing medications should measure metabolic markers and study the links between changes in metabolic markers and changes in depression. Additionally, it is important to use novel outcomes in these studies, such as changes in cognitive functioning and to investigate not only acute, but also prophylactic treatment effects.

Crosstalk between neurological, cardiovascular, and lifestyle disorders: insulin and lipoproteins in the lead role

Insulin resistance and impaired lipoprotein metabolism contribute to a plethora of metabolic and cardiovascular disorders. These alterations have been extensively linked with poor lifestyle choices, such as consumption of a high-fat diet, smoking, stress, and a redundant lifestyle. Moreover, these are also known to increase the co-morbidity of diseases like Type 2 diabetes mellitus and atherosclerosis. Under normal physiological conditions, insulin and lipoproteins exert a neuroprotective role in the central nervous system. However, the tripping of balance between the periphery and center may alter the normal functioning of the brain and lead to neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, depression, and multiple sclerosis. These neurological disorders are further characterized by certain behavioral and molecular changes that show consistent overlap with alteration in insulin and lipoprotein signaling pathways. Therefore, targeting these two mechanisms not only reveals a way to manage the co-morbidities associated with the circle of the metabolic, central nervous system, and cardiovascular disorders but also exclusively work as a disease-modifying therapy for neurological disorders. In this review, we summarize the role of insulin resistance and lipoproteins in the progression of various neurological conditions and discuss the therapeutic options currently in the clinical pipeline targeting these two mechanisms; in addition, challenges faced in designing these therapeutic approaches have also been touched upon briefly.

Family history of diabetes moderates metabolic depression endophenotypes in overweight/obese adults

OBJECTIVE

Insulin resistance (IR) is linked to depressive disorders, and there is growing evidence that targeting IR may be beneficial in treating them. We examine the association between depressive symptoms and a direct measure of IR, and whether family history of type 2 diabetes (FHx-T2DM) or major depressive disorder (FHx-MDD) moderate this relationship.

METHODS

Cross-sectional data were collected from 96 primarily overweight/obese adults ages 25-50 without diabetes or clinical depression. Multiple regression and correlation analyses were used to assess the association between depressive symptoms and a direct measure of IR (steady-state plasma glucose) as well as moderating effects of FHx-T2DM or FHx-MDD.

RESULTS

In the total sample, elevated depressive symptoms were positively associated with IR (p = 0.005). IR was associated with depressive symptoms in subjects with FHx-T2DM (p = 0.002) or FHx-MDD (p = 0.009) whereas BMI was associated with depressive symptoms in subjects without FHx-T2DM (p = 0.049) or FHx-MDD (p = 0.029). The odds of being in the top tertile of IR increased with elevated depressive symptoms alone (OR, 4.22; 95%CI, 1.15 to 17.33), presence of FHx-T2DM alone (OR, 3.42; 95%CI, 1.26 to 10.00), and presence of both FHx-T2DM and elevated depressive symptoms (OR, 10.08; 95%CI, 1.94 to 96.96).

CONCLUSIONS

Our findings indicate that depressive symptoms are positively associated with a direct measure of IR in overweight/obese individuals without diabetes or clinical depression. This association is moderated by FHx-T2DM. Early identification of groups vulnerable to IR related to depressive symptomatology may be useful for determining personalized interventions that have the potential to reduce morbidity in later years.

Diabetes and mood disorders: shared mechanisms and therapeutic opportunities

OBJECTIVE

The objective of this manuscript is to provide a comprehensive and critical overview of the current evidence on the association between Diabetes mellitus (DM) and mood disorders [i.e., Major depressive disorder (MDD) and bipolar disorder (BD)], and therapeutic opportunities.

METHODS

We searched in MEDLINE (via Ovid) for placebo-controlled clinical trials published in the last 20 years that assessed drug repurposing approaches for the treatment of DM or mood disorders.

RESULTS

We found seven studies that aimed to verify the effects of antidepressants in patients diagnosed with DM, and eight studies that tested the effect of antidiabetic drugs in patients diagnosed with MDD or BD. Most studies published in the last two decades did not report a positive effect of antidepressants on glycemic control in patients with DM. On the other hand, antidiabetic drugs seem to have a positive effect on the treatment of MDD and BD.

CONCLUSIONS

While effect of antidepressants on glycemic control in patients with DM is still controversial, the use of antidiabetic drugs may be a promising strategy for patients with MDD or BD. Prospective studies are still needed.Key pointsMood disorders in patients with DM affect glycemic control, potentially increasing mortality risk.The effect of antidepressants on glycemic control in patients with DM is still controversial. The coexistence of complicated DM and a mood disorders would require a careful, individualised, and comprehensive evaluation.Insulin resistance may increase the risk of depressive symptoms and is associated with worse outcomes in BD.The use antidiabetic drugs may be a promising strategy for patients with MDD or BD. However, prospective trials are needed to prove a potential antidepressant activity of antidiabetic drugs.

Transcriptome-wide association study for postpartum depression implicates altered B-cell activation and insulin resistance

Postpartum depression (PPD) affects 1 in 7 women and has negative mental health consequences for both mother and child. However, the precise biological mechanisms behind the disorder are unknown. Therefore, we performed the largest transcriptome-wide association study (TWAS) for PPD (482 cases, 859 controls) to date using RNA-sequencing in whole blood and deconvoluted cell types. No transcriptional changes were observed in whole blood. B-cells showed a majority of transcriptome-wide significant results (891 transcripts representing 789 genes) with pathway analyses implicating altered B-cell activation and insulin resistance. Integration of other data types revealed cell type-specific DNA methylation loci and disease-associated eQTLs (deQTLs), but not hormones/neuropeptides (estradiol, progesterone, oxytocin, BDNF), serve as regulators for part of the transcriptional differences between cases and controls. Further, deQTLs were enriched for several brain region-specific eQTLs, but no overlap with MDD risk loci was observed. Altogether, our results constitute a convergence of evidence for pathways most affected in PPD with data across different biological mechanisms.

Depression and non-alcoholic fatty liver disease: Association and potential mechanisms

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, and is closely related to the high incidence of obesity, metabolic syndrome, type 2 diabetes, arteriosclerotic cardiovascular disease, and colorectal tumor. Depression is a common mental disorder that is characterized by high incidence, high recurrence rate, high disability rate, and high suicide rate, which has serious harm to patients' physical and mental health, reduce the quality of life of patients. In recent years, as more and more attention has been paid to mental health of NAFLD patients, the relationship between NAFLD and depression has become one of the hot research topics. Studies have shown that the incidence of depression in NAFLD patients is higher than that in non-NAFLD patients, and the incidence of NAFLD in depressed patients is also higher. Some research results have been published on the mechanism of comorbidity between the two. This paper reviews the research progress on the correlation and common mechanism between NAFLD and depression, aiming to lay a foundation for further research on the comorbidities of NAFLD and depression, and provide a basis and research direction for the diagnosis and treatment of patients with both comorbidities.

New Insights Into the Pivotal Role of CREB-Regulated Transcription Coactivator 1 in Depression and Comorbid Obesity

Depression and obesity are major public health concerns, and there is mounting evidence that they share etiopathophysiological mechanisms. The neurobiological pathways involved in both mood and energy balance regulation are complex, multifactorial and still incompletely understood. As a coactivator of the pleiotropic transcription factor cAMP response element-binding protein (CREB), CREB-regulated transcription coactivator 1 (CRTC1) has recently emerged as a novel regulator of neuronal plasticity and brain functions, while CRTC1 dysfunction has been associated with neurodegenerative and psychiatric diseases. This review focuses on recent evidence emphasizing the critical role of CRTC1 in the neurobiology of depression and comorbid obesity. We discuss the role of CRTC1 downregulation in mediating chronic stress-induced depressive-like behaviors, and antidepressant response in the light of the previously characterized Crtc1 knockout mouse model of depression. The putative role of CRTC1 in the alteration of brain energy homeostasis observed in depression is also discussed. Finally, we highlight rodent and human studies supporting the critical involvement of CRTC1 in depression-associated obesity.

Deletion of Crtc1 leads to hippocampal neuroenergetic impairments associated with depressive-like behavior

Mood disorders (MD) are a major burden on society as their biology remains poorly understood, challenging both diagnosis and therapy. Among many observed biological dysfunctions, homeostatic dysregulation, such as metabolic syndrome (MeS), shows considerable comorbidity with MD. Recently, CREB-regulated transcription coactivator 1 (CRTC1), a regulator of brain metabolism, was proposed as a promising factor to understand this relationship. Searching for imaging biomarkers and associating them with pathophysiological mechanisms using preclinical models can provide significant insight into these complex psychiatric diseases and help the development of personalized healthcare. Here, we used neuroimaging technologies to show that deletion of Crtc1 in mice leads to an imaging fingerprint of hippocampal metabolic impairment related to depressive-like behavior. By identifying a deficiency in hippocampal glucose metabolism as the underlying molecular/physiological origin of the markers, we could assign an energy-boosting mood-stabilizing treatment, ebselen, which rescued behavior and neuroimaging markers. Finally, our results point toward the GABAergic system as a potential therapeutic target for behavioral dysfunctions related to metabolic disorders. This study provides new insights on Crtc1's and MeS's relationship to MD and establishes depression-related markers with clinical potential.

Insulin resistance as a marker for the immune-metabolic subtype of depression

OBJECTIVE

Insulin resistance (IR), a marker of metabolic dysregulation and pro-inflammatory state, moderates the antidepressant treatment effect in patients with type 2 diabetes (T2D) and is therefore a potential marker for personalized treatment. Based on data from a light therapy trial (NTR4942), we aimed to evaluate whether 1) depression symptoms differ according to the level of IR, and 2) improvement of specific depression symptoms drive the positive effects of light therapy in those with higher IR.

METHODS

This secondary analysis in 59 individuals with depression and T2D explored differences in depressive symptom profile (30-item Inventory of Depressive Symptomatology (IDS)) at baseline and in response to light therapy (versus placebo), between lower and higher IR individuals, using Likelihood Ratio tests and Linear-by-linear association. IR was measured using the gold standard, a hyperinsulinemic-euglycaemic clamp.

RESULTS

At baseline, higher IR individuals reported more symptoms of irritability (p=0.024) anhedonia (no interest in people and activities: p=0.011; absence of pleasure and enjoyment: p=0.021), fatigue (fatigue: p=0.036; physical fatigue: p=0.035) and hypersomnia (p=0.029) relative to persons with lower IR, who reported more insomnia (nightly awakening: p=0.041; early morning awakening: p=0.012). Light therapy led to an improvement across IDS symptoms in higher IR individuals, while in lower IR individuals, light therapy improved early morning awakening (p=0.005) and interest in people and activities (p=0.015), but worsened mood (feeling sad: p=0.001; feeling irritable: p=0.002; interpersonal sensitivity: p=0.014).

CONCLUSIONS

Results add to the hypothesis of an immune-metabolic subtype of depression, and suggest that IR might be a promising focus for precision medicine.

Multidimensional predictors of antidepressant responses: Integrating mitochondrial, genetic, metabolic and environmental factors with clinical outcomes

Major depressive disorder (MDD) is a primary psychiatric illness worldwide; there is a dearth of new mechanistic models for the development of better therapeutic strategies. Although we continue to discover individual biological factors, a major challenge is the identification of integrated, multidimensional traits underlying the complex heterogeneity of depression and treatment outcomes. Here, we set out to ascertain the emergence of the novel mitochondrial mediator of epigenetic function acetyl-L-carnitine (LAC) in relation to previously described individual predictors of antidepressant responses to the insulin-sensitizing agent pioglitazone. Herein, we report that i) subjects with MDD and shorter leukocyte telomere length (LTL) show decreased levels of LAC, increased BMI, and a history of specific types of childhood trauma; and that ii) these multidimensional factors spanning mitochondrial metabolism, cellular aging, metabolic function, and childhood trauma provide more detailed signatures to predict longitudinal changes in depression severity in response to pioglitazone than individual factors. The findings of multidimensional signatures involved in the pathophysiology of depression and their role in predicting treatment outcomes provide a starting point for the development of a mechanistic framework linking biological networks and environmental factors to clinical outcomes in pursuit of personalized medicine strategies to effectively treat MDD.

Insulin receptor substrate in brain-enriched exosomes in subjects with major depression: on the path of creation of biosignatures of central insulin resistance

Insulin signaling is critical for neuroplasticity, cerebral metabolism as well as for systemic energy metabolism. In rodent studies, impaired brain insulin signaling with resultant insulin resistance (IR) modulates synaptic plasticity and the corresponding behavioral functions. Despite discoveries of central actions of insulin, in vivo molecular mechanisms of brain IR until recently have proven difficult to study in the human brain. In the current study, we leveraged recent technological advances in molecular biology and herein report an increased number of exosomes enriched for L1CAM, a marker predominantly expressed in the brain, in subjects with major depressive disorder (MDD) as compared with age- and sex-matched healthy controls (HC). We also report increased concentration of the insulin receptor substrate-1 (IRS-1) in L1CAM⁺ exosomes in subjects with MDD as compared with age- and sex-matched HC. We found a relationship between expression of IRS-1 in L1CAM⁺ exosomes and systemic IR as assessed by homeostatic model assessment of IR in HC, but not in subjects with MDD. The increased IRS-1 levels in L1CAM⁺ exosomes were greater in subjects with MDD and were associated with suicidality and anhedonia. Finally, our data suggested sex differences in serine-312 phosphorylation of IRS-1 in L1CAM⁺ exosomes in subjects with MDD. These findings provide a starting point for creating mechanistic framework of brain IR in further development of personalized medicine strategies to effectively treat MDD.

Reduced alcohol use in patients prescribed pioglitazone

BACKGROUND AND OBJECTIVES

Alcohol use disorder (AUD) is common and causes significant morbidity and mortality. Currently approved medications are moderately effective. Novel medications are needed to address AUD. Preliminary data suggests pioglitazone may reduce alcohol use.

METHODS

Veterans seen at the Minneapolis VA Health Care System, who were prescribed pioglitazone for diabetes between October 1, 2015 and September 30, 2016, were identified using a national VA database (N = 49). Further chart review was performed to identify all Alcohol Use Disorder Identification Test-Consumption (AUDIT-C) scores prior to starting pioglitazone. Hierarchical Linear models were used to compare all AUDIT-C scores on and off pioglitazone and compare the change in AUDIT-C scores over time before and during pioglitazone was prescribed. AUDIT-C scores were nested within subject with fixed effects for pioglitazone and random intercept and slope for time.

RESULTS

Forty-nine patients were prescribed pioglitazone and had AUDIT-C scores of 3 or more. The estimated mean AUDIT-C score prior to receiving pioglitazone was 3.98 (95% confidence interval [CI]: 3.51-4.44) and this was reduced to 2.89 (95% CI: 2.46-3.32), reflecting a significant change F(1, 323) = 43.3, p < .001 in the score. The primary reduction occurred within the first year of the pioglitazone prescription. This effect remained significant after controlling for age.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

This is the first study of pioglitazone used in a clinical sample focused on alcohol use outcome. The data show that pioglitazone may reduce alcohol use in patients with heavy drinking. Clinical trials of pioglitazone are warranted in patients with AUD.

Targeting Metabolic Dysfunction for the Treatment of Mood Disorders: Review of the Evidence

Major depressive disorder (MDD) and bipolar disorder (BD) are often chronic with many patients not responding to available treatments. As these mood disorders are frequently associated with metabolic dysfunction, there has been increased interest in novel treatments that would target metabolic pathways. The objectives of this scoping review were to synthesize evidence on the impact on mood symptoms of lipid lowering agents and anti-diabetics drugs, while also reviewing current knowledge on the association between mood disorders and dyslipidemia or hyperglycemia. We propose that metabolic dysfunction is prevalent in both MDD and BD and it may contribute to the development of these disorders through a variety of pathophysiological processes including inflammation, brain structural changes, hormonal alterations, neurotransmitter disruptions, alteration on brain cholesterol, central insulin resistance, and changes in gut microbiota. Current evidence is conflicting on the use of statins, polyunsaturated fatty acids, thiazolidinediones, glucagon-like peptide agonists, metformin, or insulin for the treatment of MDD and BD. Given the paucity of high-quality randomized controlled trials, additional studies are needed before any of these medications can be repurposed in routine clinical practice. Future trials need to enrich patient recruitment, include evaluations of mechanism of action, and explore differential effects on specific symptom domains such as anhedonia, suicidality, and cognition.

Treatment-Resistant Depression Revisited: A Glimmer of Hope

Major Depressive Disorder (MDD) is a highly prevalent psychiatric disorder worldwide. It causes individual suffering, loss of productivity, increased health care costs and high suicide risk. Current pharmacologic interventions fail to produce at least partial response to approximately one third of these patients, and remission is obtained in approximately 30% of patients. This is known as Treatment-Resistant Depression (TRD). The burden of TRD exponentially increases the longer it persists, with a higher risk of impaired functional and social functioning, vast losses in quality of life and significant risk of somatic morbidity and suicidality. Different approaches have been suggested and utilized, but the results have not been encouraging. In this review article, we present new approaches to identify and correct potential causes of TRD, thereby reducing its prevalence and with it the overall burden of this disease entity. We will address potential contributory factors to TRD, most of which can be investigated in many laboratories as routine tests. We discuss endocrinological aberrations, notably, hypothalamic-pituitary-adrenal (HPA) axis dysregulation and thyroid and gonadal dysfunction. We address the role of Vitamin D in contributing to depression. Pharmacogenomic testing is being increasingly used to determine Single Nucleotide Polymorphisms in Cytochrome P450, Serotonin Transporter, COMT, folic acid conversion (MTHFR). As the role of immune system dysregulation is being recognized as potentially a major contributory factor to TRD, the measurement of C-reactive protein (CRP) and select immune biomarkers, where testing is available, can guide combination treatments with anti-inflammatory agents (e.g., selective COX-2 inhibitors) reversing treatment resistance. We focus on established and emerging test procedures, potential biomarkers and non-biologic assessments and interventions to apply personalized medicine to effectively manage treatment resistance in general and TRD specifically.

Association between depression and nonalcoholic fatty liver disease: Contributions of insulin resistance and inflammation

BACKGROUND

It is unclear whether depression is linked to nonalcoholic fatty liver disease (NAFLD). The purpose of this study was to examine the association between depression and NAFLD and whether the association is partly explained by insulin resistance or inflammation.

METHODS

Subjects consisted of 4,688 adults who participated in the 2016 Korea National Health and Nutrition Examination Survey. Depression was defined by Patient Health Questionnaire-9 score ≥ 10 or a previous diagnosis of depression. NAFLD was defined by hepatic steatosis index >36. Insulin resistance was assessed by triglycerides and glucose (TyG) index. Inflammation was measured with C-reactive protein (CRP).

RESULTS

Depression had a significant association with TyG index (p = 0.005), but not with CRP. Depression was a significant predictor of NAFLD (OR = 1.63; 95% CI, 1.26-2.10; p < 0.001). Adjustment for sociodemographic features and waist circumference did not substantially affect the results. Further adjustment for comorbidities reduced the estimate for depression by 23% (OR = 1.56; 95% CI, 1.18-2.06; p = 0.002). Inclusion of CRP in a fully adjusted model did not affect the results. Addition of the TyG index decreased the estimate for depression by 28% (OR = 1.39; 95% CI, 0.88-2.19; p = 0.161), and the resulting estimate became no longer significant. The TyG index remained the independent predictor of outcome.

LIMITATIONS

The absence of a structured diagnostic interview for depression and histological diagnosis of NAFLD.

CONCLUSIONS

These data support an association of depression with NAFLD. Insulin resistance seems to play a major role in modulating the association between depression and NAFLD risk.

Clinical Evidence of Antidepressant Effects of Insulin and Anti-Hyperglycemic Agents and Implications for the Pathophysiology of Depression-A Literature Review

Close connections between depression and type 2 diabetes (T2DM) have been suggested by many epidemiological and experimental studies. Disturbances in insulin sensitivity due to the disruption of various molecular pathways cause insulin resistance, which underpins many metabolic disorders, including diabetes, as well as depression. Several anti-hyperglycemic agents have demonstrated antidepressant properties in clinical trials, probably due to their action on brain targets based on the shared pathophysiology of depression and T2DM. In this article, we review reports of clinical trials examining the antidepressant effect of these medications, including insulin, metformin, glucagon like peptide-1 receptor agonists (GLP-1RA), and peroxisome proliferator-activated receptor (PPAR)-γ agonists, and briefly consider possible molecular mechanisms underlying the associations between amelioration of insulin resistance and improvement of depressive symptoms. In doing so, we intend to suggest an integrative perspective for understanding the pathophysiology of depression.

Evaluation of the effect of insulin sensitivity-enhancing lifestyle- and dietary-related adjuncts on antidepressant treatment response: A systematic review and meta-analysis

Background

Depression is associated with insulin resistance (IR). However, the potential beneficial effect, on antidepressant treatment response, of adjunctive therapy with insulin sensitivity-enhancing lifestyle and dietary interventions (exercise; supplementation with: vitamin D, magnesium, zinc, probiotics or omega-3 fatty acids) has not been systematically explored.

Aims

To determine the effect of the above stated adjuncts on antidepressant treatment response in clinically depressed patients via a systematic review and meta-analysis.

Methods

RCTs which assessed the effect, on antidepressant treatment response of adjunctive therapy with any of the interventions in comparison with treatment as usual were included.

Results

The interventions had a significant antidepressant effect, with SMD for follow-up (end of study) scores and change (from baseline) scores being -0.88, [95% CI: -1.19 to -0.57; P < 0.001] and -1.98 [95% CI -2.86 to -1.10; P < 0.001], respectively. The odds ratio (OR) for remission was 2.28 (95% CI 1.42 to 3.66; P < 0.001). The number-needed-to-treat (NNT) for remission was 6. Subgroup analysis of the follow-up scores revealed age effect: SMD significant in those with mean age ≤50 (-1.02 SMD; 95% CI: -1.40 to -0.64; p < 0.001) and insignificant in those with mean age >50 (-0.38 SMD (95% CI: -0.82 to 0.05; P = 0.08)). Also, the interventions were more beneficial among outpatients- SMD: -0.97 (95% CI: -1.32 to -0.62; P < 0.001) compared to inpatients- SMD: -0.34 (95% CI: -0.88 to 0.20; P = 0.22). Sensitivity analysis did not change the results.

Conclusion

The finding that antidepressant treatment response may be improved using insulin sensitivity-enhancing lifestyle and dietary adjuncts is worthy of further exploration.

PPAR and functional foods: Rationale for natural neurosteroid-based interventions for postpartum depression

Allopregnanolone, a GABAergic neurosteroid and progesterone derivative, was recently approved by the Food and Drug Administration for the treatment of postpartum depression (PPD). Several mechanisms appear to be involved in the pathogenesis of PPD, including neuroendocrine dysfunction, neuroinflammation, neurotransmitter alterations, genetic and epigenetic modifications. Recent evidence highlights the higher risk for incidence of PPD in mothers exposed to unhealthy diets that negatively impact the microbiome composition and increase inflammation, all effects that are strongly correlated with mood disorders. Conversely, healthy diets have consistently been reported to decrease the risk of peripartum depression and to protect the body and brain against low-grade systemic chronic inflammation. Several bioactive micronutrients found in the so-called functional foods have been shown to play a relevant role in preventing neuroinflammation and depression, such as vitamins, minerals, omega-3 fatty acids and flavonoids. An intriguing molecular substrate linking functional foods with improvement of mood disorders may be represented by the peroxisome-proliferator activated receptor (PPAR) pathway, which can regulate allopregnanolone biosynthesis and brain-derived neurotropic factor (BDNF) and thereby may reduce inflammation and elevate mood. Herein, we discuss the potential connection between functional foods and PPAR and their role in preventing neuroinflammation and symptoms of PPD through neurosteroid regulation. We suggest that healthy diets by targeting the PPAR-neurosteroid axis and thereby decreasing inflammation may offer a suitable functional strategy to prevent and safely alleviate mood symptoms during the perinatal period.

The Novel Role of PPAR Alpha in the Brain: Promising Target in Therapy of Alzheimer's Disease and Other Neurodegenerative Disorders

Peroxisome proliferator activated receptor alpha (PPAR-α) belongs to the family of ligand-regulated nuclear receptors (PPARs). These receptors after heterodimerization with retinoid X receptor (RXR) bind in promotor of target genes to PPAR response elements (PPREs) and act as a potent transcription factors. PPAR-α and other receptors from this family, such as PPAR-β/δ and PPAR-γ are expressed in the brain and other organs and play a significant role in oxidative stress, energy homeostasis, mitochondrial fatty acids metabolism and inflammation. PPAR-α takes part in regulation of genes coding proteins that are involved in glutamate homeostasis and cholinergic/dopaminergic signaling in the brain. Moreover, PPAR-α regulates expression of genes coding enzymes engaged in amyloid precursor protein (APP) metabolism. It activates gene coding of α secretase, which is responsible for non-amyloidogenic pathway of APP degradation. It also down regulates β secretase (BACE-1), the main enzyme responsible for amyloid beta (Aβ) peptide release in Alzheimer Diseases (AD). In AD brain expression of genes of PPAR-α and PPAR-γ coactivator-1 alpha (PGC-1α) is significantly decreased. PPARs are altered not only in AD but in other neurodegenerative/neurodevelopmental and psychiatric disorder. PPAR-α downregulation may decrease anti-oxidative and anti-inflammatory processes and could be responsible for the alteration of fatty acid transport, lipid metabolism and disturbances of mitochondria function in the brain of AD patients. Specific activators of PPAR-α may be important for improvement of brain cells metabolism and cognitive function in neurodegenerative and neurodevelopmental disorders.

Is There a Future for PPARs in the Treatment of Neuropsychiatric Disorders?

Recently, peroxisome proliferator-activated receptor (PPAR)-α and γ isoforms have been gaining consistent interest in neuropathology and treatment of neuropsychiatric disorders. Several studies have provided evidence that either the receptor expression or the levels of their endogenously-produced modulators are downregulated in several neurological and psychiatric disorders and in their respective animal models. Remarkably, administration of these endogenous or synthetic ligands improves mood and cognition, suggesting that PPARs may offer a significant pharmacological target to improve several neuropathologies. Furthermore, various neurological and psychiatric disorders reflect sustained levels of systemic inflammation. Hence, the strategy of targeting PPARs for their anti-inflammatory role to improve these disorders is attracting attention. Traditionally, classical antidepressants fail to be effective, specifically in patients with inflammation. Non-steroidal anti-inflammatory drugs exert potent antidepressant effects by acting along with PPARs, thereby strongly substantiating the involvement of these receptors in the mechanisms that lead to development of several neuropathologies. We reviewed running findings in support of a role for PPARs in the treatment of neurological diseases, including Alzheimer's disease or psychiatric disorders, such as major depression. We discuss the opportunity of targeting PPARs as a future pharmacological approach to decrease neuropsychiatric symptoms at the same time that PPAR ligands resolve neuroinflammatory processes.

Depression-like behavior, hyperglycemia, oxidative stress, and neuroinflammation presented in diabetic mice are reversed by the administration of 1-methyl-3-(phenylselanyl)-1H-indole

Oxidative stress and neuroinflammation are found both in diabetes mellitus and major depressive disorder (MDD). In addition to damage in peripheral organs, such as liver and kidney, diabetic patients have a higher risk of developing depression. In this sense, the objective of the present study was to characterize the antidepressant-like effect of a selenium-containing compound, the 1-methyl-3-(phenylselanyl)-1H-indole (MFSeI), in streptozotocin (STZ)-induced diabetic mice. STZ (200 mg/kg, i.p.) was used to induce diabetes mellitus type I, and after seven days, the administration of MFSeI (10 mg/kg, i.g.) was initiated and followed for the next 14 days. Twenty-four hours after the last administration of MFSeI, the behavioral tests were performed, followed by euthanasia. The treatment with MFSeI was able to reverse the hyperglycemia induced by STZ. MFSeI also decreased the plasma levels of biomarkers of liver and kidney damage. Importantly, MFSeI reversed the depression-like behavior induced by STZ in the tail suspension test and forced swimming test without promoting locomotor alterations. Furthermore, MFSeI reversed the increased levels of reactive species and lipid peroxidation in the prefrontal cortex (PFC), hippocampus (HC), liver, and kidney of STZ-treated mice. Treatment with MFSeI also decreased the expression of tumor necrosis factor-alpha, inducible nitric oxide synthase and indoleamine 2,3-dioxygenase, while increasing the expression of interleukin-10, insulin receptor substrate-1 and glucose transport-4 in the PFC and HC of mice. Taken together, the results indicate the effectiveness of MFSeI against depression-like behavior and central and peripheral complications caused by diabetes in mice.

Investigation of mitochondrial DNA copy number in patients with major depressive disorder

Mitochondrial dysfunction is implicated in the pathophysiology of major depressive disorder (MDD). This dysfunction can be indirectly assessed using the mitochondrial DNA (mtDNA) copy number. A total of 118 patients with MDD and 116 age- and sex-matched control subjects were recruited for this study, and mtDNA copy numbers were measured in peripheral blood cells. This study also examined the potential variables that might impact mtDNA copy number in MDD, including age and clinical features. Additionally, epigenetic control of mtDNA copy number was examined by assessing DNA methylation ratios in the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) promoter in nuclear DNA and the displacement loop (D-loop) region of mtDNA. The present results showed that patients with MDD had a higher mtDNA copy number and a decreased DNA methylation status in the PGC1α promoter. mtDNA copy numbers were negatively associated with an age, psychomotor agitation, and somatic symptoms in MDD. These results suggest that the alterations in mitochondrial function and epigenetic change of PGC1α may be relevant to the pathophysiology of MDD.

Exploration and Development of PPAR Modulators in Health and Disease: An Update of Clinical Evidence

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that govern the expression of genes responsible for energy metabolism, cellular development, and differentiation. Their crucial biological roles dictate the significance of PPAR-targeting synthetic ligands in medical research and drug discovery. Clinical implications of PPAR agonists span across a wide range of health conditions, including metabolic diseases, chronic inflammatory diseases, infections, autoimmune diseases, neurological and psychiatric disorders, and malignancies. In this review we aim to consolidate existing clinical evidence of PPAR modulators, highlighting their clinical prospects and challenges. Findings from clinical trials revealed that different agonists of the same PPAR subtype could present different safety profiles and clinical outcomes in a disease-dependent manner. Pemafibrate, due to its high selectivity, is likely to replace other PPARα agonists for dyslipidemia and cardiovascular diseases. PPARγ agonist pioglitazone showed tremendous promises in many non-metabolic disorders like chronic kidney disease, depression, inflammation, and autoimmune diseases. The clinical niche of PPARβ/δ agonists is less well-explored. Interestingly, dual- or pan-PPAR agonists, namely chiglitazar, saroglitazar, elafibranor, and lanifibranor, are gaining momentum with their optimistic outcomes in many diseases including type 2 diabetes, dyslipidemia, non-alcoholic fatty liver disease, and primary biliary cholangitis. Notably, the preclinical and clinical development for PPAR antagonists remains unacceptably deficient. We anticipate the future design of better PPAR modulators with minimal off-target effects, high selectivity, superior bioavailability, and pharmacokinetics. This will open new possibilities for PPAR ligands in medicine.

Sex-specific roles of cellular inflammation and cardiometabolism in obesity-associated depressive symptomatology

BACKGROUND

Obesity and depression are complex conditions with stronger comorbid relationships among women than men. Inflammation and cardiometabolic dysfunction are likely mechanistic candidates for increased depression risk, and their prevalence differs by sex. Whether these relationships extend to depressive symptoms is poorly understood. Therefore, we analyzed sex in associations between inflammation and metabolic syndrome (MetS) criteria on depressive symptomatology. Specifically, we examined whether sex positively moderates the relationship between depressive symptoms and inflammation among women, and whether MetS has parallel effects among men.

METHODS

Depressive symptoms, MetS, and inflammation were assessed in 129 otherwise healthy adults. Depressive symptoms were assessed using Beck Depression Inventory (BDI-Ia). Monocyte inflammation regulation (BARIC) was quantified using flow cytometry measurement of TNF-α suppression by β-agonist. Moderation effects of sex on associations between BARIC, MetS criteria, and BDI were estimated using two-way ANOVA and linear regression, adjusting for BMI, and by sex subgroup analyses.

RESULTS

Obese individuals reported more depressive symptoms. Sex did not formally moderate this relationship, though BDI scores tended to differ by BMI among women, but not men, in subgroup analysis. Poorer inflammation control and higher MetS criteria were correlated with somatic depressive symptoms. Sex moderated associations between MetS criteria and somatic symptoms; among men, MetS criteria predicted somatic symptoms, not among women. Subgroup analysis further indicated that poorer inflammation control tended to be associated with higher somatic symptoms in women.

CONCLUSIONS

These results indicate that obesity-related inflammation and MetS factors have sex-specific effects on depressive symptoms in a non-clinical population. Although pathophysiological mechanisms underlying sex differences remain to be elucidated, our findings suggest that distinct vulnerabilities to depressive symptoms exist between women and men, and highlight the need to consider sex as a key biological variable in obesity-depression relationships. Future clinical studies on comorbid obesity and depression should account for sex, which may optimize therapeutic strategies.

Insulin resistance takes center stage: a new paradigm in the progression of bipolar disorder

Bipolar Disorder (BD) is a major psychiatric illness affecting up to 5% of the population. BD can progress over time to a chronic "neuroprogressive" course with cognitive and functional impairment. Currently, there are no validated predictors indicating which patients will develop a neuroprogressive course and there are no specific treatments. This review presents data supporting a novel hypothesis on the mechanisms underlying bipolar neuroprogression. Insulin resistance (IR) is present in 52% of BD patients and is associated with chronic course, treatment nonresponse, adverse brain changes and cognitive impairment. Further, bipolar morbidity increases 12-fold following the onset of IR indicating that IR may modify disease progression. I review evidence that IR is a testable and treatable modifying factor in neuroprogression and that reversing IR may be an efficient (and perhaps the only) means of obtaining remission in some patients. I draw a parallel with Helicobacter pylori in peptic ulcer disease (a novel mechanism that brought together two previously unrelated phenomena that uncovered a new treatment approach). This model of bipolar progression combines shared dysregulated mechanisms between IR and BD, allowing for early screening, case finding, and monitoring for neuroprogression, with the potential for intervention that could prevent advanced bipolar illness. KEY MESSAGES Neuroprogression in bipolar disorder is defined by a more severe form of illness and poor outcome. Currently, there are no validated predictors of neuroprogression, which could help inform treatment and improve prognosis. Insulin resistance is present in more than half of all bipolar patients and is associated with a chronic course of illness, lack of response to mood stabilizing treatment, cognitive impairment and poor functional outcomes. Insulin resistance may modify the course of bipolar disorder and promote neuroprogression. Insulin resistance may be a testable and potentially modifiable risk factor for neuroprogression in bipolar disorder.

Efficacy of anti-inflammatory treatment on major depressive disorder or depressive symptoms: meta-analysis of clinical trials

BACKGROUND

No study has gathered evidence from all randomized clinical trials (RCTs) with anti-inflammatory drugs measuring antidepressant effects including a detailed assessment of side-effects and bias.

METHODS

We performed a systematic review identifying RCTs published prior to January 1, 2018, studying antidepressant treatment effects and side-effects of pharmacological anti-inflammatory intervention in adults with major depressive disorder (MDD) or depressive symptoms. Outcomes were depression scores after treatment, remission, response, and side-effects. Pooled standard mean differences (SMD) and risk ratios (RR) including 95% confidence intervals (95%-CI) were calculated.

RESULTS

We identified 36 RCTs, whereof 13 investigated NSAIDs (N = 4214), 9 cytokine inhibitors (N = 3345), seven statins (N = 1576), 3 minocycline (N = 151), 2 pioglitazone (N = 77), and 2 glucocorticoids (N = 59). Anti-inflammatory agents improved depressive symptoms compared to placebo as add-on in patients with MDD (SMD = -0.64; 95%-CI = -0.88, -0.40; I²  = 51%; N = 597) and as monotherapy (SMD = -0.41; 95%-CI = -0.60, -0.22; I²  = 93%, N = 8825). Anti-inflammatory add-on improved response (RR = 1.76; 95%-CI = 1.44-2.16; I²  = 16%; N = 341) and remission (RR = 2.14; 95%-CI = 1.03-4.48; I²  = 57%; N = 270). We found a trend toward an increased risk for infections, and all studies showed high risk of bias.

CONCLUSION

Anti-inflammatory agents improved antidepressant treatment effects. Future RCTs need to include longer follow-up, identify optimal doses and subgroups of patients that can benefit from anti-inflammatory intervention.

Depression precedes, but does not follow, gestational diabetes

OBJECTIVES

To determine whether past history of depression is associated with increased rates of gestational diabetes, and whether history of gestational diabetes is associated with increased rates of postpartum depression.

RESEARCH DESIGN

Data for this case-control study consisted of de-identified chart records for 1439 women who received pregnancy care at a large university hospital between 1998 and 2017.

RESULTS

A history of depression prior to pregnancy was associated with gestational diabetes requiring insulin, although not with subtler degrees of gestational hyperglycemia. Diabetes in pregnancy was not associated with an increased risk of postpartum depression. Trauma history was associated with both impaired glucose tolerance in pregnancy and postpartum depression.

CONCLUSIONS

Past episodes of depression increase risk for the most severe form of gestational diabetes; however, gestational diabetes does not contribute significantly to risk for postpartum depression. This suggests a unidirectional association, unlike the bidirectional association of diabetes with depression among the general population. History of trauma increases risk for both gestational hyperglycemia and postpartum depression, suggesting important health effects of trauma that may differ measurably from those associated with depression.

Effects of Light Therapy on Mood and Insulin Sensitivity in Patients With Type 2 Diabetes and Depression: Results From a Randomized Placebo-Controlled Trial

OBJECTIVE

Depression is common in patients with type 2 diabetes and adversely affects quality of life and diabetes outcomes. We assessed whether light therapy, an antidepressant, improves mood and insulin sensitivity in patients with depression and type 2 diabetes.

RESEARCH DESIGN AND METHODS

This randomized, double-blind, placebo-controlled trial included 83 patients with depression and type 2 diabetes. The intervention comprised 4 weeks of light therapy (10,000 lux) or placebo light therapy daily at home. Primary outcomes included depressive symptoms (Inventory of Depressive Symptomatology [IDS]) and insulin sensitivity (M-value derived from the results of a hyperinsulinemic-euglycemic clamp). Secondary outcomes were related psychological and glucometabolic measures.

RESULTS

Intention-to-treat analysis showed that light therapy was not superior to placebo in reducing depressive symptoms (-3.9 IDS points [95% CI -9.0 to 1.2]; P = 0.248) and had no effect on insulin sensitivity (0.15 mg/kg*min [95% CI -0.41 to 0.70]; P = 0.608). Analyses incorporating only those participants who accurately adhered to the light therapy protocol (n = 51) provided similar results, but did suggest positive effects of light therapy on depression response rates (≥50% reduction in IDS points) (26% more response; P = 0.031). Prespecified analysis showed effect moderation by baseline insulin sensitivity (P = 0.009) and use of glucose-lowering medication (P = 0.023). Light therapy did not affect depressive symptoms in participants with higher insulin sensitivity or those who use only oral glucose-lowering medication or none at all, but it did produce a relevant effect in participants with lower insulin sensitivity (-12.9 IDS points [95% CI -21.6 to -4.2]; P = 0.017) and a trend toward effectiveness in those using insulin (-12.2 IDS points [95% CI -21.3 to -3.1]; P = 0.094). Light therapy was well tolerated.

CONCLUSIONS

Although this trial is essentially inconclusive, secondary analyses indicate that light therapy might be a promising treatment for depression among a subgroup of highly insulin-resistant individuals with type 2 diabetes.

Evaluation of the effect of insulin sensitivity-enhancing lifestyle- and dietary-related adjuncts on antidepressant treatment response: protocol for a systematic review and meta-analysis

BACKGROUND

Depression is the leading cause of disability worldwide and is known to be associated with insulin resistance (IR). Insulin resistance worsens the symptoms of depression and reduces the effectiveness of antidepressant medications in some depressed patients. Many studies have assessed the effect of adjunctive exercise, vitamin D supplementation, zinc supplementation, magnesium, probiotics, unsaturated fatty acids, and hygienic-dietary recommendations (sleep hygiene, healthy diet, physical activity, and sunlight exposure, combined or singly used), individually, on antidepressant treatment response. However, despite the reported insulin sensitivity-enhancing potential of these adjuncts, no systematic review has collectively analysed their antidepressant effect with regards to insulin sensitivity.

METHODS/DESIGN

In this systematic review, we will analyse the effect of the above-stated adjuncts on antidepressant treatment response (primary outcome) in comparison with treatment as usual with or without adjunctive placebo after identifying the relevant trials from a systematic literature search. Randomised controlled trials involving clinically depressed patients with diagnosis of major depressive, dysthymic or bipolar disorder will be considered. Changes in insulin sensitivity parameters, following treatment, will also be analysed as the secondary outcome. Effect estimates of the included trials will be combined using random-effects meta-analysis, while addressing risk of bias issues. Any significant heterogeneity between studies will be explored using sensitivity and subgroup analyses.

DISCUSSION

The findings of this review will contribute to the evidence base regarding the utility of non-pharmacological insulin-sensitising treatments in enhancing conventional antidepressant treatment response.

Double-blind, placebo-controlled trial of pioglitazone for bipolar depression

BACKGROUND

Objective of the present study was to conduct an 8-week double-blind, randomized, placebo-controlled trial to test the efficacy of pioglitazone in the treatment of bipolar depression.

METHODS

38 outpatients with bipolar disorder and current major depressive episode were randomized to pioglitazone (15-45 mg/day) or placebo. The use of concomitant mood stabilizers, antipsychotics, and antidepressants was permitted. The primary outcome measure was the 30-item Inventory of Depressive Symptomatology, Clinician Rated (IDS-C30) total score change from baseline to endpoint. Laboratory evaluations, including serum level of inflammatory and metabolic biomarkers, were conducted.

RESULTS

37 subjects were analyzed for efficacy (1 subject had no follow-up data). Mean reduction from baseline to week 8 in IDS-C30 score was-6.59 for pioglitazone and -11.63 for placebo. Mixed effects modeling indicated borderline statistically significant difference between the two groups (p = 0.056) in favor of placebo. On analysis of inflammatory and metabolic markers, a statistically significant negative correlation was noted between change in leptin levels and change in depression scores in the pioglitazone group (r = -0.61, p = 0.047) but not in the placebo group, the significance of which is unclear as the study failed to demonstrate antidepressant efficacy of pioglitazone over placebo. No serious adverse effects were reported, and pioglitazone was well-tolerated.

LIMITATIONS

small sample size with inadequate power, concomitant use of other psychotropic medications, and lack of statistical adjustment for multiple testing.

CONCLUSION

Current study does not support the antidepressant efficacy of pioglitazone in the treatment of bipolar depression. (240 words).

Childhood trauma and insulin resistance in patients suffering from depressive disorders

OBJECTIVE

Insulin resistance (IR) is a metabolic dysfunction often co-morbid with major depressive disorder (MDD). The paths to development of MDD remain largely unspecified, highlighting a need for identification of risk factors. Here, we tested whether specific subscales of childhood trauma as well as family history of type-2 diabetes (Fam-Hx-Dm2) are risk factors for development of metabolic dysfunction and severity of depressive symptoms.

RESEARCH DESIGN AND METHODS

We used a sample of 45 adults suffering from MDD that was well-characterized for insulin resistance and sensitivity as assessed by measures of fasting plasma glucose (FPG) plasma insulin (FPI) levels, body mass index (BMI), weight, homeostasis model assessment of insulin sensitivity (HOMA), Matsuda index as well as both glucose and insulin responses to oral glucose challenges. Severity of depressive symptoms was assessed with the Hamilton Depression Rating Scale (HDRS-21). Physical, sexual and emotional abuse as well as physical and emotional neglect were assessed with the Childhood Trauma Questionnaire. First- or second-degree relatives with type-2 diabetes defined fam-Hx-DM2.

RESULTS

Individuals reporting higher rates of emotional abuse were more likely to have greater IR as showed by elevated FPI levels and HOMA. No association was found with any of the other subscales of childhood trauma (e.g., physical abuse). Similarly, Fam-Hx-DM2 was associated with greater degree of IR as shown by elevated FPI, HOMA, but also FPG, weight and BMI. Moreover, we report a relationship and interaction between Fam-Hx-DM2 and emotional abuse on severity of depressive symptoms. Specifically, emotional abuse and Fam-HX-DM2 predicted severity of depressive symptoms at HDRS-21. Also, severity of depressive symptoms was greater with higher reported rates of emotional abuse but only in patients with negative Fam-Hx-Dm2. Individuals reporting higher emotional abuse and negative Fam-Hx-Dm2 also showed higher FPG levels. Conversely, individuals reporting higher emotional abuse and positive Fam-Hx-Dm2 showed higher FPI levels. This data suggest that Fam-Hx-Dm2 may define two different metabolic endophenotypes.

CONCLUSIONS

Our findings suggest that Fam-HX-DM2 and emotional abuse represent separate risk factors for developing metabolic dysfunction (i.e.: IR) in patients suffering from MDD, and that the effects of emotional abuse on psychiatric illness may depend upon the personal characteristics, including Fam-Hx-DM2.

Insulin Resistance as a Shared Pathogenic Mechanism Between Depression and Type 2 Diabetes

Neuropsychiatric disorders and type 2 diabetes (T2D) are major public health concerns proposed to be intimately connected. T2D is associated with increased risk of dementia, neuropsychiatric and mood disorders. Evidences of the involvement of insulin signaling on brain mechanisms related to depression indicate that insulin resistance, a hallmark of type 2 diabetes, could develop in the brains of depressive patients. In this article, we briefly review possible molecular mechanisms associating defective brain insulin signaling with reward system, neurogenesis, synaptic plasticity and hypothalamic-pituitary-adrenal (HPA) stress axis in depression. We further discuss the involvement of tumor necrosis factor α (TNFα) promoting defective insulin signaling and depressive-like behavior in rodent models. Finally, due to the high resistant rate of anti-depressants, novel insights into the link between insulin resistance and depression may advance the development of alternative treatments for this disease.

Early life adversity blunts responses to pioglitazone in depressed, overweight adults

PURPOSE

Early life adversity is associated with both metabolic impairment and depression in adulthood, as well as with poorer responses to antidepressant medications. It is not yet known whether individual differences in sensitivity to antidiabetic medications could also be related to early life adversity. We examined whether a history of early life adversity affected the observed changes in metabolic function and depressive symptoms in a randomized trial of pioglitazone for augmentation of standard treatments for depression.

PURPOSE

Early life adversity is associated with both metabolic impairment and depression in adulthood, as well as with poorer responses to antidepressant medications. It is not yet known whether individual differences in sensitivity to antidiabetic medications could also be related to early life adversity. We examined whether a history of early life adversity affected the observed changes in metabolic function and depressive symptoms in a randomized trial of pioglitazone for augmentation of standard treatments for depression.

FINDINGS

We found that early life adversity significantly impaired the metabolic response to pioglitazone. Effects on depressive symptoms did not reach significance, but nonetheless suggested that pioglitazone could mitigate the depressant effects of childhood adversity, only among those insulin resistant at baseline.

CONCLUSIONS

We conclude that a history of early life adversity may impair the body's ability to respond to insulin sensitizing pharmacotherapy, and furthermore that its contribution to resistant depression may function in part via the generation of an insulin resistant phenotype.

Cognitive effects of mifepristone in overweight, euthymic adults with depressive disorders

BACKGROUND

Previous studies have shown that individuals with mood disorders have a higher prevalence of both hypercortisolemia and insulin resistance. Insulin resistance is posited to contribute to the cognitive deficits observed in individuals who have depression. However, the mechanistic relationship between cortisol and insulin within the central nervous system remains to be further elucidated. This study aimed to evaluate the effects of the antiglucocorticoid agent, mifepristone, on metabolic function and cognitive performance in individuals receiving treatment for depressive disorders who were euthymic at baseline.

METHODS

Participants were administered a 600 mg/day dose of mifepristone for 28 days. Oral glucose tolerance tests (OGTTs) and cognitive assessments measuring verbal memory and executive functioning were administered at baseline and after 28 days of treatment.

RESULTS

Improvements in attention and verbal learning were associated with reduction of fasting plasma glucose (FPG) in response to mifepristone treatment.

LIMITATIONS

Limitations include the open-label design of this study and a small sample size.

CONCLUSIONS

The findings from this study suggest that improvement in fasting plasma glucose levels, upon administration of mifepristone, is associated with the improvement in early input of verbal information. Further studies are warranted in order to better evaluate the use of mifepristone or other antiglucocorticoid agents in treatment of mood disorders characterized by metabolic dysfunction.

Repositioning of diabetes treatments for depressive symptoms: A systematic review and meta-analysis of clinical trials

Depression is a common comorbidity in diabetes but conventional antidepressant treatments do not consistently improve outcomes. We tested whether established diabetes treatments can also improve depressive symptoms and examined biological correlates of response. We performed a multi-database systematic search of all clinical trials, which measured the effect of licensed diabetes treatments on depressive symptoms using a validated questionnaire. Results of randomised controlled trials (RCT's) were pooled for meta-analysis. Data were also collected on insulin resistance (HOMA-IR), C-reactive protein (CRP) and fasting blood glucose (FBG) as correlates of response. Nineteen studies (n = 3369 patients) were included in the qualitative synthesis, 9 testing thiazolidenediones, 5 metformin, 2 thiazolidenediones against metformin, 2 incretin-based therapies and 1 insulin. Most studies were of good quality. In random-effects meta-analysis of RCT's, pioglitazone improved depressive symptoms compared to controls (pooled effect size = -0.68 (95% C.I. -1.12 to -0.24), p = .003, N_studies = 8, I² = 83.2%). Conversely, metformin was comparable to controls overall (pooled effect size = +0.32 (95% C.I. -0.23 to 0.88), p = .25, N_studies = 6, I² = 94.2%), although inferior to active controls (pooled effect size = +1.32 (95% C.I. 0.31-2.34), p < 0.001, N_studies = 3, I² = 90.1%). In random-effects meta-regression, female sex (β = -0.023, (95% C.I.-0.041 to -0.0041), p = .016, N_studies = 8) predicted reduction in depressive symptoms with pioglitazone, but baseline HOMA-IR, FBG and severity of depressive symptoms did not. In conclusion, pioglitazone was associated with improvement in depressive symptoms, an effect more marked in women and poorly explained by effects on glycaemia and insulin resistance. Metformin had no consistent benefit on depressive symptoms. Further mechanistc trials of diabetes treatments as potential antidepressants are needed, stratified by sex and including serial measures of innate inflammation.

Acetyl-l-carnitine deficiency in patients with major depressive disorder

The lack of biomarkers to identify target populations greatly limits the promise of precision medicine for major depressive disorder (MDD), a primary cause of ill health and disability. The endogenously produced molecule acetyl-l-carnitine (LAC) is critical for hippocampal function and several behavioral domains. In rodents with depressive-like traits, LAC levels are markedly decreased and signal abnormal hippocampal glutamatergic function and dendritic plasticity. LAC supplementation induces rapid and lasting antidepressant-like effects via epigenetic mechanisms of histone acetylation. This mechanistic model led us to evaluate LAC levels in humans. We found that LAC levels, and not those of free carnitine, were decreased in patients with MDD compared with age- and sex-matched healthy controls in two independent study centers. Secondary exploratory analyses showed that the degree of LAC deficiency reflected both the severity and age of onset of MDD. Moreover, these analyses showed that the decrease in LAC was larger in patients with a history of treatment-resistant depression (TRD), among whom childhood trauma and, specifically, a history of emotional neglect and being female, predicted the decreased LAC. These findings suggest that LAC may serve as a candidate biomarker to help diagnose a clinical endophenotype of MDD characterized by decreased LAC, greater severity, and earlier onset as well as a history of childhood trauma in patients with TRD. Together with studies in rodents, these translational findings support further exploration of LAC as a therapeutic target that may help to define individualized treatments in biologically based depression subtype consistent with the spirit of precision medicine.

A review of brain insulin signaling in mood disorders: From biomarker to clinical target

Patients with mood disorders are at increased risk for metabolic dysfunction. Co-occurrence of the two conditions is typically associated with a more severe disease course and poorer treatment outcomes. The specific pathophysiological mechanisms underlying this bidirectional relationship between mood and metabolic dysfunction remains poorly understood. However, it is likely that impairment of metabolic processes within the brain play a critical role. The insulin signaling pathway mediates metabolic homeostasis and is important in the regulation of neurotrophic and synaptic plasticity processes, including those involved in neurodegenerative diseases like Alzheimer's. Thus, insulin signaling in the brain may serve to link metabolic function and mood. Central insulin signaling is mediated through locally secreted insulin and widespread insulin receptor expression. Here we review the preclinical and clinical data addressing the relationships between central insulin signaling, cellular metabolism, neurotrophic processes, and mood regulation, including key points of mechanistic overlap. These relationships have important implications for developing biomarker-based diagnostics and precision medicine approaches to treat severe mood disorders.

Peroxisome Proliferator-Activated Receptor Gamma Coactivator-1 Alpha as a Novel Target for Bipolar Disorder and Other Neuropsychiatric Disorders

Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1 alpha) is a protein that regulates metabolism and inflammation by activating nuclear receptors, especially the family of peroxisome proliferator-activated receptors (PPARs). PGC-1 alpha and PPARs also regulate mitochondrial biogenesis, cellular energy production, thermogenesis, and lipid metabolism. Brain energy metabolism may also be regulated in part by the interaction between PGC-1 alpha and PPARs. Because neurodegenerative diseases (Huntington's disease, Parkinson's disease, and amyotrophic lateral sclerosis) and bipolar disorder have been associated with dysregulated mitochondrial and brain energy metabolism, PGC-1 alpha may represent a potential drug target for these conditions. The purpose of this article is to review the physiology of PGC-1 alpha, PPARs, and the role of PPAR agonists to target PGC-1 alpha to treat neurodegenerative diseases and bipolar disorder. We also review clinical trials of repurposed antidiabetic thiazolidines and anti-triglyceride fibrates (PPAR agonists) for neurodegenerative diseases and bipolar disorder. PGC-1 alpha and PPARs are innovative potential targets for bipolar disorder and warrant future clinical trials.

Redefining neuroendocrinology: Epigenetics of brain-body communication over the life course

The brain is the central organ of stress and adaptation to stress that perceives and determines what is threatening, as well as the behavioral and physiological responses to the stressor, and it does so somewhat differently in males and females. The expression of steroid hormone receptors throughout the brain has broadened the definition of 'neuroendocrinology' to include the reciprocal communication between the entire brain and body via hormonal and neural pathways. Mediated in part via systemic hormonal influences, the adult and developing brain possess remarkable structural and functional plasticity in response to stress, including neuronal replacement, dendritic remodeling, and synapse turnover. This article is both an account of an emerging field elucidating brain-body interactions at multiple levels, from molecules to social organization, as well as a personal account of my laboratory's role and, most importantly, the roles of trainees and colleagues, along with my involvement in interdisciplinary groups working on this topic.